Tcell activation

O Whether it is by the direct or indirect pathway, in order for a T cell to become activated against the transplanted organ, two interactions, or signals must take place

between the APCs and the recipient's T cells ' :

• Signal 1 is the interaction of the TCR with the foreign antigens presented by the APCs.

• A second, costimulatory signal, known as Signal 2, must also take place for T-cell activation. This signal is an interaction between one of several costimulatory receptors and paired ligands on the cell surfaces of the APCs and T cells, respectively. This interaction is of the utmost importance, as Signal 1 in the absence of Signal 2 induces T-cell anergy.

Once activated, T cells undergo clonal expansion under the influence of cytokines, specifically interleukin-2 (IL-2). These steps elicit an antidonor T-cell response that results in graft destruction.

Stop Headache Drug Free

Stop Headache Drug Free

If you are suffering from headaches, you can make the pain stop just by following some basic but little known principles. Take 15 minutes browsing through this guide and you'll find dozens of tips to gain control in the battle against headache pain.

Get My Free Audio Book


Post a comment